Treatment or manufacture of cellulose ester material



Patented Sept. 7, 1937 TREATMENT OR MANUFACTURE OF CELLU LOSE ESTER MATERIAL Robert Wighton Moncriefl' and Frank Brentnall Hill, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application December 6, 1934, Se-

rial No. 756,283. 12, 1933 15 Claims.

This invention relates to the manufacture or treatment of filaments, threads, yarns, ribbons and the like having a basis of cellulose acetate or other organic ester of cellulose.

It is known to saponify cellulose ester materials and also to stretch such materials witha view to increasing their tenacity. We have now found a means of stretching the materials to a considerable extent and of saponifying them simultaneously. When it is attempted to stretch inan ordinary alkaline saponifying bath, for instance v a caustic soda bath, serious difliculties are encountered. Apart from the difliculty of effecting a substantial degree of stretch in such baths, even in the presence of a softening agent for the mate rial, there is the difliculty that such stretch as is effected tends to render the materials brittle and/or harsh to the touch and in other respects to injure their serimetric properties. We have found that by treating cellulose acetate threads and like materials in a bath containing a. nonmetallic base, for example mono-methylamine, which bath is capable of softening the base of the materials, stretching may actually be effected simultaneously with saponification with most valuable results. The process of the invention makes it possible to obtain from ordinary cellulose acetate materials in a single operation, materials of high tensile strength, good extensibility and low denier. These materials may have an aflinity for cotton dyes as well as for cellulose ester dyes. The process can be carried out rapidly and continuously. The saponification effected may extend to a considerable depth beneath the surface,

or even throughout the whole section of the mate-' connection with the treatment of filaments,

threads, ribbons, fabrics and like materials having a basis of cellulose acetate and will be described with special reference to the treatmentof such materials. 7

4 The materials treated may be made by any suitable dry or wet spinning method. Where high tenacity is required in the final products it is of particular advantage to produce the filaments and tone, diacetone alcohol,

In Great Britain December the like by wet spinning methods in the course of which they are stretched to a considerable extent, or to soften and stretch the materials after their production whether by a wet or a dry spinning process. By applying the process of the invention to materials which have been stretched considerably, for example to 200% of their original length or even more, materials of particularly valuable serimetric properties are obtainable.

The non-metallic base preferably comprises mono-methylamine. Other strong aliphatic organic bases, for example ethylamine, propylamine, amylamine and triethylamine, may also be employed. Again, somewhat weaker bases of the same series, for example trimethylamine and alllylamine, may be used. Further, considerably stronger bases of the same series may beemployed, even very strong bases such as tetramethyl ammonium hydroxide, provided care be taken. to avoid damaging the materials. Again, amines containing more than one amino group, and particularly aliphatic diamines of relatively lowmolecular weight, for example ethylene diamine, symmetrical dimethyl ethylene diamine, monomethyl ethylene diamine, and propylene diamine may also be used. Preferably atleast one of the amino groups of such amines should be unsubstituted or mono-substituted. Amines containing more than two amino groups may also be employed, for example 1.2;3-triamino propane. The effect of one or more hydroxy groups in the amine appears to be to favour the penetration of the materials by the saponifying agent, and with this object in view substances of the type of wy-diamino-p-hydroxy propane may be used with advantage. Again, bases of the heterocyclic series, for example piperidine may be used. The bath may contain substances adapted to accelerate the action of thenon-metallic base. Various inorganic substances 'which may be employed for this purpose are mentioned in U. S. application S. Nos. 756,282, 756,284,. and 756,285, filed December 6, 1934. Among such substances special mention may be made of caustic soda. and of copper in solution in connection with saponification by means of methylamine or other lower aliphatic amines.

.I'he swelling agent is preferably a swelling agent of relatively high solvent power for the base of the materials. Thus in the case of cellulose acetate, we may employ for example, acecyclohexanol, cyclohexanone, methyl cyclohexanone, 'dioxane or methylene ethylene ether.

The process is preferably effected by drawing the materials through an aqueous bath containing the swelling agent centrations will generally along the the'bath. It is of advantage to treat a large number of ends at one time, drawing them through the bath in warp formation, that is in substantially parallel relationship one with another and in the same plane, by means of a series of rollers, reeds being employed where necessary tain the warp formation. The speeds-of successive sets of rollers may increase progressively path of the materials so as to insert progressively increasing stretch. On the other hand, stretching may be effected in stages between which the materials are allowed to relax under substantially no tension. ample, the materials may pass from. the feed rollers through a set of rollers rotating at a higher speed so as to impart a stretch, then through a set rotating at a slightly lower speed than the second set, and from thence through a set rotating at a higher speed than the second set. The materials are preferably stretched to 150 or 200% or more of their original length.

The concentration of swelling agent and base in the bath and the temperature of the bath may vary according to the extent of saponification and of stretch 'to be effected. Generally speaking, temperatures of the order of 15-20" C. or 25-35 C. will be found convenient.

20 and 40 or 60% will generally be found suitable; In the case of the non-metallic base suitable con and 5 or a v .The degree of saponification effected may be sufficient to produce a loss in the acidyl content of the ester of 10-15% or even less, but is preferably somewhat greater, for example sufiicient to produce a loss in the acidyl content of 20-25%.

The following example illustrates the invention:-

Example Cellulose acetate yarn is drawn in warp formation through an aqueous bath containing 35-45% dioxane. The speed of travel of the material is such that it is in contact with the bath for 1-3 minutes and is stretched to ISO-200% of its original length during the passage through the bath. The bath contains mono-methylamine in a proportion depending upon the amount of saponification to be effected. On leaving the bath the materials pass through a short washing bath and then over heated drums to suitable winding means.

Although the invention has been described with particular reference to the treatment of materials having a basis of cellulose acetate, it is also applicable to the treatment of other materials containing saponifiable esters of cellulose, for example cellulose formate, propionate, bu-

tyrate, ethyl cellulose acetate, oxyethyl cellulose acetate and nitrocellulose acetate.

What we claim and desire to secure by Letters Patent is:--

1. Process for the manufacture of improved artificial materials, which comprises softening and partially saponifying filaments, threads, ribbons and like materials having a basis of organic esters of cellulose by treatment with a swelling bath which contains a non-aromatic nitrogenous organic base which contains less than seven carbon atoms, and stretching the softened materials during saponification.

2. Process for the manufacture of improved artificial materials, which comprises softeningv to main- Thus, for ex-- For they swelling agent an aqueous concentration between he found between and non-metallic base and and partially saponifying filaments, threads, ribbons and like materials having a basis of organic esters of cellulose by treatment with a swelling bath which contains a nitrogenous organic base, having less than seven carbon atoms, of dissooiation constant at least as high as trimethylamine, and stretching the softened materials during saponification.

3. Process for the manufacture of improved artificial materials, which comprises softening and partially saponifying filaments, threads, ribbons and like materials having a basis of cellulose acetate by treatment with a swelling bath which contains a non-aromatic nitrogenous organic base which contains less than seven carbon atoms, and stretching the softened materials during saponification.

4. Process for the manufacture of improved artificial materials, which comprises softening and partially saponi'fying filaments, threads, ribbons and like materials having a basis of cellulose acetate by treatment with a swelling bath which contains a water-soluble nitrogenous base containing less than seven carbon atoms in which each carbon atom that is directly attached to a nitrogen atom is directly attached to three other atoms apart from said nitrogon atom, and stretching the softened materials during saponification.

5. Process for the manufacture of improved artificial materials, which comprises simulta- -;n'eously softening and partially saponifying fila- J'ments, threads, ribbons and like materials havli e a basis of organic esters of cellulose by drawing the materials through an aqueous softening bath containing a neutral swelling agent for the organic ester of cellulose and a non-aromatic nitrogenous organic base which contains less than seven carbons atoms, and stretching the softened materials during their passage through said bath.

6. Process for the manufacture of improved artificial materials, which comprises. simultaneously softening and partially saponifylng filaments, threads, ribbons and like materials having a basis of organic esters of cellulose by drawing the materials through an aqueous softening bath containing a neutral swelling agent for the organic ester of cellulose and mono-methylamine, and stretching the softened materials during their passage through said bath.

7. Process for the manufacture of improved artificial materials, which comprises simultaneously softening and partially saponifying filaments, threads, ribbons and like materials having a basis of cellulose acetate by drawing the materials through an aqueous softening bath containing a neutral swelling agent for cellulose acetate and a lower aliphatic amine, and stretching the softened materials during their passage through said bath.

.8. Process for the manufacture of improved artificial materials which comprises simultaneously softening and partially saponifying filaments, threads, ribbons and like materials having a basis of cellulose acetate by drawing the materials through an aqueous softening bath containing a neutral swelling agent for the cellulose acetate and mono-methylamine, and stretching the sofigenerild materials during their passage through said at v 9. Process for the manufacture of improved artificial materials which comprises simultaneously softening and partially saponifying filaments, threads, ribbons and like materials having a basis of cellulose acetate by drawing the materials through an aqueous softening taining a neutral swelling agent for the cellulose acetate and ethylene diamine, and stretching the softened materials during their passage through said bath. a i

10. Process for the manufacture of improved artificial materials, which comprises softening and partially saponifying filaments, threads, ribbons and like materials having a basis of organic esters of cellulose by treatment with a swelling bath which contains a non-aromatic nitrogenous organic base which contains less than seven carbon atoms, so as to effect a loss of 1025 of the acidyl content, and stretching the softened materials during saponification.

11. Process for the manufacture of improved artificial materials, which comprises softening and partially saponifying filaments, threads, ribbons and like materials having a basis of organic esters of cellulose by subjecting the materials'to the action of a swelling bath containing a watersoluble nitrogenous base containing less than seven carbon atoms in which each carbon atom that is directly attached to a nitrogen atom is directly attached to three other atoms apart from said nitrogen atom and a small quantity of a mineral alkali, and stretching the softened materials during saponification.

12. Process for the manufacture of improved artificial materials, which comprises softening and partially saponifying filaments, threads, ribbons and like materials having a basis-of organic esters of cellulose by subjecting the materials to the action of a swelling b athcontaining a nonaromatic nitrogenous organic base which contains less than seven carbon atoms and a small quan tity of copper in solution, and stretching the softened materials during saponification.

13. Process for the manufacture of improved artificial materials, which comprises simultaneously softening and partially saponifying filaments, threads, ribbons and like materials having a basis of cellulose acetate by drawing the materials through an equeous softening bath containing a neutral swelling agent for cellulose acetate, mono-methylamine and a small quantity of copper in solution, and stretching the softened materials during their passage through said bath.

14. Process for the manufacture of improved artificial materials, which comprises drawing filaments, threads, ribbons or like materials having a basis of cellulose acetate, in warp formation through an aqueous dioxane bath containing mono-methylamine, so as to efiect a relatively deep-seated saponification resulting in a loss of 10-20% of the acetyl content, and stretching the materials to at least of their original length during their passage through said bath.

15. Process for the manufacture of improved artificial materials, which comprises drawing filaments, threads, ribbons or like materials having a basis of cellulose acetate, in warp formation through an aqueous acetone bath containing mono-methylamine, so as to effect a relatively deep-seated saponification resulting in a loss of 10-20% of the acetyl content and stretching the materials to at least 150% of their original length during their passage through said bath.

ROBERT WIGHTON MONCRIEFF. FRANK BRENTNALL HILL. 

